1. Field of the Invention
The present invention relates to a display device, a terminal device, a display panel, and a display device driving method, which are capable of displaying images to each of a plurality of viewpoints. More specifically, the present invention relates to a display device, a terminal device, a display panel, and a display device driving method, which are capable of suppressing deterioration in the image quality caused when writing video signal on a single row of pixels in a time division manner.
2. Description of the Related Art
Owing to the recent technical developments, display panels are used in various places by being loaded not only to large-scale terminal devices such as monitors and television receiver sets but also to medium-scale terminal devices such as notebook-type personal computers, cash dispensers, and vending machines, and to small-scale terminal devices such as personal TVs, PDAs (Personal Digital Assistances), portable telephones, and portable game machines. Particularly, liquid crystal display devices using liquid crystal have many advantages such as being thin in thickness, light in weight, small in size, and low in terms of power consumption, so that those are loaded to various terminal devices. With a current display device, same display contents as those when viewed from a front direction can be observed from places other than the front direction. However, a display device with which different images can be observed depending on the viewpoints, i.e., depending on the positions from which observers views the display, has also been deployed. Such device is expected to grow as a display device of next generation.
As an example of the device capable of displaying different images to each of a plurality of viewpoints, there is a stereoscopic image display device. Particularly, a lenticular lens type and parallax barrier type have been proposed as a stereoscopic image display system that requires no special eye glasses.
Further, as another example of the device capable of displaying different images for each of a plurality of viewpoints, there has been deployed a plural-image simultaneous displaying device that is capable of displaying a plurality of different images for a plurality of viewpoints simultaneously (see Japanese Unexamined Patent Publication 06-332354 (Patent Document 1), for example). This is a display that displays different images for each observing direction simultaneously under a same condition by utilizing an image allotting function of a lenticular lens. This makes it possible with a single display device to provide different images simultaneously to a plurality of observers that are located different positions from each other with respect to the display device.
In the meantime, conventionally, a block division driving method has been proposed (see Japanese Examined Patent Publication 06-80477 (FIG. 4) (Patent Documents 2) and Japanese Unexamined Patent Publication 2006-154808 (Patent Documents 3), for example) as one of liquid crystal display device driving methods. FIG. 41 is a circuit diagram showing the block division driving method. As shown in FIG. 41, output lines D1-Dm from a source line driver part 500D as a video output circuit are put together into one block by every m-number of output lines by a matrix circuit 502. Provided that the number of blocks is k, there are “m×k”-number of video signal lines obtained from an “m×k” matrix. The m-number of video signal lines S1 -Sm on each block are connected to the matrix circuit 502 via a block division TFT array 501 that is controlled by output lines B1-Bk from a TFT array driver part 500B. A single pixel 500U is disposed at each intersection point of the matrix configured by the “m×k”-number of video signal lines and output lines G1-Gm from a gate line driver part 500G.
Operations of the liquid crystal display device depicted in Patent Document 2 will be described. The output line G1 is selected by an output from the gate line driver part 500G. Within this one horizontal period, an output line B1 is selected by an output from the TFT array driver part 500B. Then, a signal outputted from the source line driver part 500D is transmitted to the video signal lines S1-Sm of the first block that is selected by the output line B1. Then, when an output line B2 is selected, a video signal is transmitted to the video signal lines S1-Sm of the second block. This operation is repeated. When an output line Bk is selected, a video signal is transmitted to the video signal lines of the k-th block. Thereby, one horizontal period ends. One screen can have an image displayed thereon by repeating a series of operations in one horizontal period. By writing the video signals in divided blocks, it is possible with the block division driving method to reduce the number of connections greatly. In addition, it is also possible to reduce the scale of the source line driver circuit. This makes it possible to improve the reliability and to cut the cost.
However, there has been found that block division causes deterioration in the display quality of the display device with the above-described block division driving method. In this deterioration of the picture quality, luminance differences are generated between edges of the blocks and other parts in particular even when same video information is written thereto, which generates block-like unevenness. As described, the driving method which supplies the video signals in a time-division manner generates deterioration in the display image quality caused due to the division.
The inventors of the present invention have zealously conducted studies and found that there is also other type of deterioration generated in the display image quality than the conventional block-like unevenness, when the division driving method such as the block division driving method is employed for the above-described plural-viewpoint display device that is capable of displaying different images towards a plurality of viewpoints.